﻿// ConsoleTools
// Copyright (C) 2017-2024 Dust in the Wind
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

// --------------------------------------------------------------------------------
// Bugs or feature requests
// --------------------------------------------------------------------------------
// Note: For any bug or feature request please add a new issue on GitHub: https://github.com/lastunicorn/ConsoleTools/issues/new/choose

using System;
using System.IO;

namespace DustInTheWind.ConsoleTools;

internal abstract class ThreeStageFile : IDisposable
{
    private readonly string targetFileName;
    private readonly string tempFileName;
    private readonly string backupFileName;

    public FileStream FileStream { get; private set; }

    protected ThreeStageFile(string fileName)
    {
        targetFileName = fileName ?? throw new ArgumentNullException(nameof(fileName));

        tempFileName = $"{fileName}.tmp";
        backupFileName = $"{fileName}.bak";
    }

    public void Open()
    {
        if (FileStream != null)
            return;

        if (File.Exists(tempFileName))
            throw new ApplicationException($"The previous process was not completed. Delete the temporary {tempFileName} file and then try again.");

        FileStream = File.OpenWrite(tempFileName);
    }

    public void Close()
    {
        if (FileStream == null)
            return;

        FileStream.Close();
        FileStream.Dispose();
        FileStream = null;

        if (File.Exists(targetFileName))
            File.Replace(tempFileName, targetFileName, backupFileName);
        else
            File.Move(tempFileName, targetFileName);
    }

    public void Dispose()
    {
        FileStream?.Dispose();
    }
}